The invention relates to certain multidentate phosphite ligands, the catalyst compositions made therefrom and catalytic processes which employ such multidentate phosphite ligands. In particular, the ligands have heteroatom-containing substituents on the carbon attached to the ortho position of the terminal phenol group. The catalytic processes exemplified herein are hydrocyanation and isomerization.
Phosphorus ligands are ubiquitous in catalysis and are used for a number of commercially important chemical transformations. Phosphorus ligands commonly encountered in catalysis include phosphines (A), and phosphites (B), shown below. In these representations, R can be virtually any organic group. Monophosphine and monophosphite ligands are compounds which contain a single phosphorus atom which serves as a donor to a metal. Bisphosphine, bisphosphite, and bis(phosphorus) ligands in general, contain two phosphorus donor atoms and normally form cyclic chelate structures with transition metals. 
There are several industrially important catalytic processes employing phosphorus ligands. For example, U.S. Pat. No. 5,910,600 to Urata, et al. discloses that bisphosphite compounds can be used as a constituting element of a homogeneous metal catalyst for various reactions such as hydrogenation, hydroformylation, hydrocyanation, hydrocarboxylation, hydroamidation, hydroesterification and aldol condensation.
Some of these catalytic processes are used in the commercial production of polymers, solvents, plasticizers and other commodity chemicals. Consequently, due to the extremely large worldwide chemical commodity market, even small incremental advances in yield or selectivity in any of these commercially important reactions are highly desirable. Furthermore, the discovery of certain ligands that may be useful for applications across a range of these commercially important reactions is also highly desirable not only for the commercial benefit, but also to enable consolidation and focusing of research and development efforts to a particular group of compounds.
U.S. Pat. No. 5,512,696 to Kreutzer, et al. discloses a hydrocyanation process using a multidentate phosphite ligand, and the patents and publications referenced therein describe hydrocyanation catalyst systems pertaining to the hydrocyanation of thylenically unsaturated compounds. U.S. Pat. Nos. 5,723,641, 5,663,369, 5,688,986 and 5,847,191 disclose processes and catalyst compositions for the hydrocyanation of monoethylenically unsaturated compounds using zero-valent nickel and multidentate phosphite ligands, and Lewis acid promoters.
U.S. Pat. No. 5,821,378 to Foo, et al. discloses a liquid phase process for the hydrocyanation of diolefinic compounds to produce nonconjugated acyclic nitriles as well as a liquid phase process for the isomerization of those nitriles to 3- and/or 4-monoalkene linear nitrites where the reactions are carried out in the presence of zero-valent nickel and a multidentate phosphite ligand. Other catalytic processes for the hydrocyanation of olefins and the isomerization of monoalkene nitrites are described in the patents and publications referenced therein. Commonly assigned, published PCT Application WO99/06357 discloses multidentate phosphite ligands having alkyl ether substituents on the carbon attached to the ortho position of the terminal phenol group for use in a liquid phase process for the hydrocyanation of diolefinic compounds to produce nonconjugated acyclic nitrites as well as a liquid phase process for the isomerization of those nitrites to 3- and/or 4monoalkene linear nitrites.
While the catalyst systems described above may represent commercially viable catalysts, it always remains desirable to provide even more effective, higher performing catalyst precursor compositions, catalytic compositions and catalytic processes to achieve full commercial potential for a desired reaction. The effectiveness and/or performance may be achieved in any or all of rapidity, selectivity, efficiency or stability, depending on the reaction performed. It is also desirable to provide such improved catalyst systems and/or processes which may be optimized for one or more commercially important reactions such as hydroformylation, hydrocyanation or isomerization. Other objects and advantages of the present invention will become apparent to those skilled in the art upon reference to the detailed description which hereinafter follows.
The invention provides for a hydrocyanation process comprising reacting an acyclic, aliphatic, monoethylenically unsaturated compound in which the ethylenic double bond is not conjugated to any other olefinic group in the molecule with a source of HCN in the presence of a catalyst precursor composition comprising a Lewis acid, a zero-valent nickel and at least one, multidentate phosphite ligand selected from the group represented by the following formulae I, I-A or I-B, in which all like reference characters have the same meaning, except as further explicitly limited. 
wherein X1 is a bridging group selected from the group consisting of: 
wherein R1, R2, R3, R4, R5, R6, R7, R8, R1xe2x80x2, R2xe2x80x2 are independently selected from the group consisting of H, C1 to C18 alkyl, cycloalkyl, trialkylsilyl, triarylsilyl, halogen, nitrile, perfluoroalkyl, xe2x80x94SO2R11, xe2x80x94SO2NR212, acetal, ketal, dialkylamnino, or diarylamino, xe2x80x94OR11, xe2x80x94CO2R11, xe2x80x94(CNR11)R11, xe2x80x94(CNOR11)R11, wherein R11 is C1 to C18 alkyl, aryl, or substituted aryl, xe2x80x94C(O)R12, xe2x80x94C(O)NR12R13, xe2x80x94Oxe2x80x94C(O)R12, xe2x80x94NR12xe2x80x94C(O)R13, wherein R12 and R13 are independently selected from the group of H, C1 to C18 alkyl, cycloalkyl, aryl, or substituted aryl; wherein positions other than R1 through R8 on the aromatic rings may also be substituted with C1 to C18 alkyl, cycloalkyl, trialkylsilyl, triarylsilyl, halogen, nitrile, perfluoroalkyl, sulfonyl, acetal, ketal, dialkylamino, diarylamino, xe2x80x94OR11, xe2x80x94CO2R11,R CNR11, or RCNOR11,
wherein R9 and R10 are independently selected from the group consisting of H, C1 to C18 alkyl, cycloalkyl, aryl, or substituted aryl;
wherein X2 through X5 are independently selected from the group consisting of: 
wherein Y is independently selected from the group consisting of H, aryl, CR143, wherein R14 is H, C1-C18 alkyl, cycoalkyl, or aryl, (CR142)nxe2x80x94OR14, (CR142)nxe2x80x94NHR15, wherein n=0-3, wherein R15 is selected from the group consisting of H, alkyl, aryl, xe2x80x94SO2R11, xe2x80x94SO2NR122, xe2x80x94COR16, wherein R16 is H, C1-C18 alkyl, cycloalkyl, aryl or perfluoroalkyl;
and Z is selected from tile group consisting of (CR142)nxe2x80x94OR14 wherein n=0-3 and R14 is defined as above. 
In other embodiments of the invention a ligand of the structure of Formula I-A may be substituted for the ligand of Formula I, and in those embodiments an aromatic ring carbon in the ortho position to an O bonded to a P may be bonded through (Z1)n1 to another aromatic ring carbon in the ortho position to the other O bonded to the P;
wherein Z1 is independently 
and each of R17 and R18 are independently selected from the group consisting of H, C1 to C18 alkyl, cycloalkyl, aryl, or substituted aryl, n1 is either one or zero; and wherein it is understood that n1=0 represents a bond replacing the two aromatic ring hydrogens. 
In other embodiments of the invention a ligand of the structure of Formula I-B may be substituted for the ligand of Formula l, and wherein an aromatic ring carbon in the ortho position to an O bonded to a P may be bonded through (Z1)n1 to another aromatic ring carbon in the ortho position to the other O bonded to the P;
wherein Z1 is independently 
and each of R17 and R18 are independently selected from the group consisting of H, C1 to C18 alkyl, cycloalkyl, aryl, or substituted aryl, n1 is either one or zero; and wherein it is understood that n1=0 represents a bond replacing the two aromatic ring hydrogens.
Furthermore, in embodiments of the invention utilizing Formula I, Formula I-A or Formula I-B, either one of the Y""s may be linked with Z to form a cyclic ether. In such embodiments, at least one of the groups X2-X5 may have the structure of formulae A or B wherein Y3=O or CH2; and R14 is defined as above: 
The invention also provides for a multidentate phosphite ligand having the structure represented by the following Formula II, Formula II-A or Formula II-B in which all like reference characters have the same meaning, except as further explicitly limited. 
wherein X1 is a divalent bridging group and is selected from the group consisting of: 
wherein R1, R2, R3, R4, R5, R6, R7, R8, R1xe2x80x2, and R2xe2x80x2 are independently selected from the group consisting of H, C1 to C18 alkyl, cycloalkyl, trialkylsilyl, triarylsilyl, halogen, nitrile, perfluoroalkyl, xe2x80x94SO2R11, xe2x80x94SO2NR212, acetal, ketal, dialkylamino, or diarylamino, xe2x80x94OR11, xe2x80x94CO2R11, xe2x80x94(CNR11)R11, xe2x80x94(CNOR11)R11, wherein R11 is C1 to C18 alkyl, cycloalkyl, aryl, or substituted aryl, xe2x80x94C(O)R12, xe2x80x94C(O)NR12R13, xe2x80x94Oxe2x80x94C(O)R12, xe2x80x94NR12xe2x80x94C(O)R13, wherein R12 and R13 are independently selected from the group of H, C1 to C18 alkyl, cycloalkyl, aryl, or substituted aryl; wherein positions other than R1 through R8 on the aromatic rings may also be substituted with C1 to C18 alkyl, cycloalkyl, trialkylsilyl, triarylsilyl, halogen, nitrile, perfluoroalkyl, sulfonyl, acetal, ketal, dialkylamino, diarylamino, xe2x80x94OR11, xe2x80x94CO2R11, R CNR11, or RCNOR11, wherein R9 and R10 are independently selected from the group consisting of H, C1 to C18 alkyl, cycloalkyl, aryl, or substituted aryl,
wherein X2 through X5 are independently selected from the group consisting of: 
Y1 is independently selected from the group consisting of H, aryl, CR143, wherein R14 is H, C1-C18 alkyl, cycloalkyl, or aryl, (CR142)nxe2x80x94OR14, (CR142)nxe2x80x94NHR15 wherein n=0-3, wherein R15 is selected from the group consisting of H, alkyl, cycloalkyl, aryl, xe2x80x94SO2R11, xe2x80x94SO2NR122, xe2x80x94COR16 wherein R16 is H, C1-C18 alkyl, cycloalkyl, aryl, or perfluoroalkyl;
Y2is independently selected from the group consisting of aryl, CR143, wherein R14 is H, C1-C18 alkyl, cycloalkyl, or aryl, (CR142)nxe2x80x94OR14, (CR142)nxe2x80x94NHR15 wherein n=0-3, wherein R15 is selected from the group consisting of H, alkyl, cycloalkyl, aryl, xe2x80x94SO2R11, xe2x80x94SO2NR122, xe2x80x94COR16 wherein R16 is H, C1-C18 alkyl, cycloalkyl, aryl, or perfluoroalkyl;
Z is selected from the group consisting of (CR142)nxe2x80x94OR14 wherein n=0-3 and wherein R14 is defined as above. 
In other embodiments of the invention a ligand of the structure of Formula II-A may be substituted for the ligand of Formula II, and wherein an aromatic ring carbon in the ortho position to an O bonded to a P may be bonded through (Z1)n1 to another aromatic ring carbon in the ortho position to the other O bonded to the P;
wherein Z1 is independently 
and each R17 and R18 are independently selected from the group consisting of H, C1 to C18 alkyl, cycloalkyl, aryl, or substituted aryl, n1 is either one or zero; and wherein it is understood that n1=0 represents a bond replacing the two aromatic ring hydrogens. 
In other embodiments of the invention a ligand of the structure of Formula II-B may be substituted for the ligand of Formula II, and an aromatic ring carbon in the ortho position to an O bonded to a P maybe bonded through (Z1)n1 to another aromatic ring carbon in the ortho position to the other O bonded to the P;
wherein Z1 is independently 
and each R17 and R18 are independently selected from the group consisting of H, C1 to C18 alkyl, cycloalkyl, aryl, or substituted aryl, n1 is either one or zero; and wherein it is understood that n1=0 represents a bond replacing the two aromatic ring hydrogens.
Furthermore, in embodiments of the invention utilizing Formula II, Formula II-A or Formula II-B, either Y1 or Y2 may be linked with Z to form a cyclic ether. In such embodiments, at least one of the groups X2-X5 may have the structure of formulae A or B wherein Y3xe2x95x90O or CH2; and R14 is defined as above: 
The invention also provides for certain multidentate phosphite ligands and catalyst compositions made therefrom useful in the hydrocyanation of diolefinic compounds to produce nonconjugated acyclic nitrites as well as a liquid phase process for the isomerization of those nitrites to 3- and/or 4-monoalkene linear nitrites. In particular, these include the ligands of Formula II, Formula I-A and Formula II-B in combination with nickel.
The present invention further provides for an improved process for the hydrocyanation of diolefinis, such as butadiene, and the isomerization of nonconjugated acyclic nitrites. The present invention further provides for an improved process for the hydrocyanation of diolefins without the need for Lewis acid promoters. The multidentate phosphite ligands in these embodiments include the ligands of Formula II, Formula II-A and Formula II-B in combination with nickel wherein the ligands have heteroatom-containing substituents on the carbon attached at the ortho position of the terminal phenol groups. The present invention may also provide a catalyst having a high degree of selectivity in the hydrocyanation of diolefins such that no additional isomerization step is required.
Specifically, the present invention provides an improved process for the liquid phase hydrocyanation of diolefins and isomerization of the resulting nonconjugated acyclic nitrites comprising, reacting an acyclic aliphatic diolefin, preferably butadiene, with a source of HCN, wherein the process comprises conducting the hydrocyanation and/or isomerization in the presence of a catalyst composition comprising zero-valent nickel and at least one multidentate phosphite ligand selected from the group represented by formulae II, II-A and II-B as set forth above, in which all like reference characters have the same meaning, except as further explicitly limited:
The reactions are most conveniently performed continuously from hydrocyanation of the starting diolefin to the final 3- and/or 4-monoalkene linear nitrites. However, the processes can be conducted stepwise, i.e., the nonconjugated acyclic nitriles resulting from the hydrocyanation can be isolated per se, prior to isomerization. Furthermore, nonconjugated acyclic nitrites prepared by any method can be used as starting materials for the isomerization in accordance with this invention.